Key takeaways
- Firebase Dynamic Links shut down on August 25, 2025, leaving every app that depended on
*.page.linkURLs needing a successor. - ULink was designed as a drop-in FDL replacement: similar SDK shape, automatic AASA +
assetlinks.jsonhosting, deferred deep linking, and a real SLA. - The 2-hour migration path: audit existing links → configure your branded domain in ULink → swap the SDK dependency → flip CNAME.
- ULink unlocks features FDL never had: branded domains as standard, social meta-tag overrides per channel, geo-routing, and richer attribution.
- Start with the free tier or talk to us about a hands-on migration review.
The end of an era — and the start of a better one
The Firebase Dynamic Links (FDL) deprecation announcement and its August 25, 2025 sunset closed a chapter that lasted nearly a decade. FDL was the default for many teams because it was free and bundled into Firebase. But "free" came with trade-offs that became increasingly painful: stale documentation, opaque SDK behavior on newer iOS releases, and zero accountability when something broke at 2 a.m. on Black Friday.
If you're still running on a forked FDL build or a homegrown stopgap, you're carrying technical debt that's actively decaying. The question isn't whether to migrate — it's to what.
This guide walks through why ULink became the most common destination for FDL migrations and how to move over in roughly an afternoon.
Why FDL was sunset — and why "free" was never really free
Google's decision wasn't arbitrary. Three forces made the FDL economics untenable:
- Privacy changes. Apple's App Tracking Transparency and the rollout of Google's Privacy Sandbox broke the universal-tracking assumptions FDL was built on.
- Universal Links got harder. AASA file requirements, association limits, and the rise of social-app in-app browsers turned what was a "set and forget" service into one needing constant maintenance.
- No revenue model. A free product without a clear path to revenue rarely gets the engineering investment it needs to keep up with the OS treadmill.
Teams that depended on FDL during its final years felt all of this — flaky link resolution on new iOS releases, no support channel when things went sideways, and analytics that lagged behind what modern attribution required.
Why ULink is the logical successor
A real FDL alternative needs to do more than replicate the surface API. It needs to remove the fragility teams put up with for years.
1. A drop-in SDK shape
ULink's SDKs were intentionally designed so the migration is mostly find-and-replace. If your app already has a "deep link handler" wired into your router, you're swapping the dependency and the listener call — not redesigning your navigation graph.
2. Real reliability
ULink runs on a global CDN with monitored AASA and assetlinks.json files. Custom branded domains get auto-renewing TLS. We publish status, and customers on paid tiers get an SLA — which is what you need when a Black Friday push notification has to land.
3. Branded domains as standard
FDL's biggest user-facing complaint was the *.page.link subdomain. It read as spam to security-conscious users, and tools like iMessage and many SMS gateways treated it that way. ULink uses your domain — go.yourbrand.com, links.yourbrand.com, whatever you want. Industry benchmarks consistently show branded short links materially outperform generic ones in CTR.
4. Deferred deep linking that actually survives the App Store
ULink's deferred matching uses contextual signals (not banned fingerprinting) plus the platform-provided attribution APIs to hand the original link parameters to your app on first launch. New users land on the right screen the first time they open the app, with referral codes and discounts intact.
The 2-hour migration strategy
Most teams complete the migration in an afternoon. Here's the path.
Phase 1: Audit your existing links
Pull a list of every place an FDL URL is referenced:
- Hardcoded in transactional emails (password reset, receipt, invite)
- "Link in bio" and social profiles
- SMS templates and push-notification payloads
- QR codes printed on physical packaging
- Influencer collateral
Capture the slug, the destination route inside the app, and any campaign parameters. A spreadsheet is enough.
Phase 2: Configure ULink
In the ULink console, create your project and enter:
- iOS Bundle ID + Apple Team ID
- Android Package Name + SHA-256 fingerprint
- Your custom domain (e.g.
go.yourbrand.com)
ULink generates the AASA and assetlinks.json files automatically and hosts them. You point your domain's CNAME at ULink and TLS provisions on its own.
Phase 3: Swap the SDK
Remove firebase_dynamic_links and add flutter_ulink_sdk (Flutter shown here; iOS and Android SDKs follow the same shape).
Old (Firebase):
import 'package:firebase_dynamic_links/firebase_dynamic_links.dart';
FirebaseDynamicLinks.instance.onLink.listen((PendingDynamicLinkData data) {
handleLink(data.link);
});
New (ULink):
import 'package:flutter_ulink_sdk/flutter_ulink_sdk.dart';
final sdk = ULink.instance;
await sdk.initialize(ULinkConfig(
apiKey: 'ulk_your_api_key_here',
));
sdk.onUnifiedLink.listen((ULinkResolvedData data) {
// data.slug, data.parameters, data.linkType
handleLink(data);
});
The shape is intentionally familiar. The ULinkResolvedData object carries richer context than FDL's PendingDynamicLinkData — slug, parameters, link type, social tags, and the full original URL — so you typically gain signal in the migration rather than lose it.
Phase 4: Re-create the links
You have two options:
- Recreate in the ULink console for the dozen highest-traffic links and update the references.
- Bulk import via the REST API for everything else.
If you want to keep the old *.page.link URLs limping along during a soft cutover, you can run both in parallel for a window and watch the analytics.
What you unlock after the migration
Beyond replacing FDL feature-for-feature, ULink ships things FDL never had:
- Per-channel social meta-tag overrides. Different OG image and title for Twitter vs. WhatsApp vs. iMessage from a single canonical link.
- Geo-routing. Different store for different regions, language-specific landing routes, country-specific fallbacks — all configurable per link.
- Smart fallbacks. Don't dump desktop users on a broken App Store page. Send them to a landing page or a web version of the destination.
- Real-time analytics. Click → install → post-install events tied back to the originating campaign, with UTM passthrough into GA4 and webhooks into your data warehouse. (Measuring deep link ROI.)
- Reinstall detection. ULink can detect when a previous user reinstalls and surface that signal to your app — useful for win-back flows.
- Branded short links for SMS. A higher-trust link in the channel where trust matters most. (How branded links lift SMS CTR.)
Common migration questions
Will my existing FDL URLs keep working?
The FDL service has been shut down. Any *.page.link URLs in the wild will not resolve. The migration is to update the source of those links (emails, SMS templates, social bios, QR codes) to point at your new ULink branded domain. ULink's bulk import keeps slugs stable so the in-app routing logic doesn't have to change.
Do I have to change my app's internal routing?
Usually not. If your existing handler pattern was "parse the deep link → extract parameters → call the router," you're swapping the listener and the parameter shape. Your router stays the same.
How long does TLS / AASA propagation take?
TLS issues automatically on the ULink side once the CNAME resolves. AASA cache invalidation can take hours on iOS — if you're testing immediately, use the dashboard's link validator to verify the file is live and signed correctly.
What about the *.page.link short codes I have on physical packaging?
Those are gone. The path forward is to print a new ULink branded short link or — better — a QR code pointing at one. The QR code lets you change the destination later without reprinting.
Is deferred deep linking still possible after Apple's ATT?
Yes. ULink's deferred matching uses contextual signals and the platform attribution APIs, not banned fingerprinting. (Read the privacy-first attribution guide.)
What does ULink cost vs. FDL?
FDL was free; ULink has a free tier (see pricing) and paid plans that scale with click volume and features (branded domains, SLA, priority support). Most teams migrating from FDL fit comfortably in the free or starter tier.
Migrate when you're ready
The longer you sit on a deprecated link infrastructure, the more silent failures accumulate — broken receipts, broken referral flows, missed attribution. The migration itself is small; the cost of waiting compounds.
Create a free ULink account and run through the migration checklist, or book a 20-minute migration review with our team to scope your specific setup.